Doors of this type or of a similar type are known in various designs. Such doors must provide good protection to vehicle occupants in the event of a side impact. Moreover, they must offer the possibility to accommodate various aggregates such as window lift mechanical equipment, loudspeakers and the like.
With a door of the initially mentioned type known from applications in practice, the deep-drawn inner panel comprises the beam member for various add-on and mounting units. To obtain sufficient mounting depth for these aggregates, the inner panel must be made of good deep-drawn steel. However, such steel contributes little to stiffening of the door. Therefore, an autonomous stiffening beam made of high-strength steel sheet is mounted to the door inner panel to serve as side impact protection. Moreover, profiled elements made of high-strength steel are mounted in the reinforcement regions for the door functional elements such as hinges and lock. Owing to the multitude of individual elements to be assembled, the expenditure on fabricating such a door is high. Its ratio between stiffness and weight is not optimal either.
With another door of a motor vehicle which is known from the relevant patent literature (DE 10 2005 009 179 AI), the stiffening beam serving as side impact protection is mounted at the outer panel of the door. The plate-shaped beam member for the various add-on and mounting units is made of plastic material and formed as a hybrid component with a metallic frame. The metallic frame furnishes this hybrid component with the mounting depth required for the add-on and mounting units and it comprises the reinforcement regions for the door functional elements. This hybrid component is preferably firmly connected by a bolted union to the door outer panel and is designed to render a substantial contribution to door stiffness.
With another door of a motor vehicle which is also known from the relevant patent literature (DE 10 2005 030 507 AI), a frame-shaped reinforcing element together with the outer panel and inner panel forms a door structure. For this purpose, this element is firmly connected by joined connections such as spot welding to the outer and inner panel. The reinforcing element is made of high-strength steel and can be fabricated by hot working The reinforcing areas for hinges and for the lock are integrally configured at it. A stiffening beam serving as side impact protection extends diagonally through the frame and is an integral part of the frame. In addition to this reinforcing element arranged between the outer and inner panel, a beam for various add-on and mounting aggregates can be installed into the door. However, prior art technology does not disclose how such a beam is configured.
Finally, the relevant patent literature (DE 10 2005 005 684 AI) discloses a frame-shaped reinforcing element which is very similar to the reinforcing element of the door described hereinabove and which is also made of high-strength steel sheet and fabricated by hot working. As integral components, this reinforcing element also has reinforcing regions for the door lock and door hinges as well as a stiffening beam serving as side impact protection and extending diagonally through the frame. Such a reinforcing element is arranged between the outer panel and the inner panel of the motor vehicle door. Prior art technology available in this regard does not address the accommodation of add-on and mounting aggregates.